A digital-to-analog converter (DAC) is a device for converting a digital code to an analog signal. For example, a DAC can convert an 8-bit digital signal into an output voltage or current having an amplitude representing the digital code. Two common examples of DACs are the “R-string” DAC and the “R-2R ladder” DAC. Another example is the Parallel Resistors Architecture (PRA) digital-to-analog converter (DAC). Advantages of the PRA-DAC over the “R-string” DAC and the “R-2R ladder” DAC include that the PRA-DAC has a constant output impedance and inherent monotonicity compared to “R-2R ladder” DACs.
PRA-DACs suffer, however, from code dependent current consumption. Code dependent current consumption can severely worsen the DACs linearity, and more particularly its integral non-linearity (INL) due to unavoidable parasitic access resistance of the DACs references. Thus use of PRA-DACs is often limited to low resolution applications.